The objective of this study is to identify and characterize immune factors that can be used clinically in the treatment of cancer. During the last grant period, we identified two glycolipid antigens, gangliosides GM2 and GD2, as tumor- associated antigens of human cancer. The synthesis of pure GM2 and GD2 was performed successfully. GM2 and GD2 are capable of inducing humoral immune responses in man. Human monoclonal antibodies specific for each of these two gangliosides have been produced in this laboratory, and recently a clinical trial was initiated under a separate grant (CA42396). In this renewal application, we propose to evaluate two new areas of investigation on GM2 and GD2: (1) Cell-mediated immune responses to GM2/GD2: Our preliminary studies have indicated that GM2 is a target recognition structure for human NK cells. The proposed study includes the development of methods for detecting cell-mediated responses specific for GM2/GD2 and the establishment of natural (NK), activated (AK), and cytotoxic T-cell clones that recognize GM2/GD2 antigen structure on target cells. (2) Anti-idiotype (anti-Id) antibodies against internal images of GM2/GD2: We will establish human monoclonal anti-Id against anti-GD2/GM2 antibodies. Lymphocytes from patients receiving GM2/GD2-rich tumor cell vaccines (under Project III) and/or from patients receiving immunization with human monoclonal antibodies to GD2/GM2 will be used as B-cell sources. The proposed study is an important step in improving our current progress in developing new approaches for immunology and immunotherapy of human cancer. Further efforts to induce cell- mediated or humoral immunity against these gangliosides may lead to an effective method for specific immunization in patients with melanomas and other human tumors.